1. Field of the Invention
The present invention generally relates to the field of manufacturing, and to the production of components, such as sheet metal components. More particularly, the present invention relates to an apparatus and method for performing multi-part setup planning for carrying out sheet metal operations, such as sheet metal bending operations.
2. Background Information
Traditionally, the production of bent sheet metal components involves a series of production and manufacturing stages. The first stage is a design stage during which a sheet metal part design is developed based on a customer's specifications. A customer's order will usually include the necessary product and design information so that the component may be manufactured by a facility. During the design stage, a sheet metal part design may be developed at a design office of the manufacturing facility using an appropriate computer-aided design (CAD) system. Based on a customer's specifications, a two-dimensional (2-D) model of the sheet metal part may be developed by a programmer with a CAD system. The 2-D model may include a flat view and one or more other perspective views of the sheet metal part, with bending line and/or dimensional information.
Before actual bending of the sheet metal component can take place, the part must first be punched and/or cut from initial sheet metal stock material. Computer numerical control (CNC) or numerical control (NC) systems are typically used to control and operate punch presses and/or plasma or laser cutting machinery to process the stock material. In order to facilitate processing of the stock material, a computer-aided manufacturing (CAM) system or CAD/CAM system can be used by a design programmer to generate control code based on the 2-D model. The control code may comprise a part program that is imported to and utilized by the punch press and/or cutting machinery to punch or cut the sheet metal components from the stock material.
The next stage in the production process is a bending planning stage. During this stage, a bending plan may be developed by a bending operator at, for example, the shop floor. The operator will normally be provided with the blueprint or 2-D drawing of the component, along with one or more samples of the cut or punched stock material. With these materials, the bending operator will develop a bending plan which includes a press brake setup and bending plan that define the tooling to be used and the sequence of bends to be performed. The bending workstation may include CNC metal bending machinery, such as a CNC press brake, that enables the operator to enter data and develop a bending code or program based on the bending plan.
Once the bending plan is developed, the operator will setup the workstation for initial testing of the bending sequence. During this testing stage, the punched or cut stock material will be manually loaded into the press brake and the press brake will be operated to execute the programmed sequence of bends on the workpiece. Based on the results of the initial runs of the press brake, the operator may modify the bending sequence by editing the bending program. Further testing will typically be conducted until the bent sheet metal component is within the required design specifications.
One of the final stages in the production process is the bending stage. After the bending plan has been developed and tested, the bending operator will setup the required tooling at the bending station and operate the press brake based on the bending plan and the stored bending program code. Job scheduling is also performed in order to ensure that the necessary amount of punched or cut stock material will be available on time at the bending station and so that other jobs will be completed by the requested delivery dates. After the final bent sheet metal parts have been produced, the parts may then be assembled and packaged for shipping to the customer.
The conventional production and manufacturing process described above suffers from several drawbacks and disadvantages. For example, considerable manufacturing time is normally spent during the development of the sheet metal part design and bending plan, since the development of the part design and bending plan is primarily performed by the design programmer and the bending operator, and relies heavily on the individual's knowledge, skill and experience. Further, conventional methods, such as those described above, are not capable of efficiently handling a wide variety of product variations and customized jobs for customers. Such prior attempts focus on the design and setup for individual parts, and do not have the capacity to simultaneously consider the setup for multiple parts. In addition, past attempts which relied upon a standard or generic setup to accommodate multiple parts, fail to consider the setup constraints imposed on each part. As a result, parts frequently can not be manufactured with such a standard setup, and additional manufacturing time is often spent developing a setup for unaccommodated parts.
In recent years, there have been developments and attempts to improve the conventional sheet metal manufacturing process and to improve efficiency of the overall process. For example, computer-based systems and robotic manipulators and controllers have been developed to provide a greater level of automation in the production process of sheet metal components. Further, research and development has taken place in the field of intelligent/expert systems for automatically generating and/or providing bending plan and other manufacturing information required to produce sheet metal components. For instance, U.S. patent application Ser. No. 08/386,369, entitled "Intelligent System For Generating And Executing A Sheet Metal Bending Plan", filed on Feb. 9, 1995, in the names of David A. BOURNE et al., the contents of which is expressly incorporated herein by reference in its entirety, discloses an intelligent, automated bending system which generates a bending plan and then executes the generated bending plan to produce a bend sheet metal component. The system disclosed therein includes one or more expert modules or subsystems for providing expert information, including tooling information, to a bend sequence planner, which determines and generates a final bending plan. A sequencer is also provided for executing the final generated plan, and for formulating and transmitting the appropriate commands to the various components within the bending workstation in order to produce the bend sheet metal components. In addition, U.S. patent application Ser. No.08/338,115, entitled "Method For Planning/Controlling Robot Motion", filed on Nov. 9, 1994, in the names of David A. BOURNE et al., the contents of which is expressly incorporated herein by reference in its entirety, discloses an expert system for planning controlling the motion of a robot in order to facilitate the production of sheet metal components.
A number of new technologies have also been developed, such as flexible manufacturing systems (FMS) and modular fixturing systems to handle the increase in product variations. These technologies focus on achieving process and material handling flexibility. For more information on such systems, see, for example, LUGGEN, W. W., Flexible Manufacturing Cells and Systems, Prentice Hall, Englewood Cliffs, N.J. (1991), and MALEKI, R. A., Flexible Manufacturing Systems: The Technology and Management, Prentice Hall, Englewood Cliffs, N.J. (1991). In addition, Group Technology (GT) has been used to create better shop layouts by identifying parts with similar process plans and producing them on the same production cells. In GT approaches, part families and production cells are formed based on the use of common machines. Additional information concerning GT systems may be found in, for example, SNEAD, C. S., Group Technology: Foundations For Competitive Manufacturing, Van Nostrand Reinhold, N.Y. (1989), and GROOVER, M. P., Fundamentals of Modern Manufacturing: Materials, Processes and Systems, Prentice Hall, Upper Saddle River, N.J. (1996).
While such prior systems have increased the flexibility and automation of manufacturing systems, such attempts have failed to adequately handle a wide variety of product variations and customized jobs for customers. For example, past attempts have given very little attention in exploiting commonality in tooling and fixturing across multiple parts. Most process planners currently handle one part at a time, attempting to find the best plan for each part. Such planners fail to identify commonality among parts and cannot select common tooling in fixtures that work for multiple parts. As a result of these limitations, such systems require more frequent setup changes and, therefore, reduce the overall through-put capability of the manufacturing system. Further, since machine setups are specified by selecting particular fixtures and tooling, the ordering of new fixtures or tools for every part increases manufacturing costs and contributes to non-value added operations.
Accordingly, in view of the drawbacks of such past attempts, there is a need for the ability to simultaneously plan for multiple parts to facilitate mass customization and to significantly improve and enhance the product realization process. Since setup changes constitute a major portion of the production time in batch production environments, there is a need for an improved setup planning technique that can significantly cut down the total number of setups and increase the overall through-put of the manufacturing facility. Current process planning systems focus on individual parts, and fail to exploit the commonality between setups for different parts that may be utilized to determine shared or composite setup plans to produce each of the parts. Further, with the increasing emphasis on more personalized products and shrinking product lives, there is a need for new manufacturing techniques for handling mass customization and a wider variety of product mix on the shop floors with increased product through-put.